A whole new regime of science and applications is opened by the ability to switch nanophotonic structures very quickly while light propagates through them. This will allow the catching or releasing of photons, or changing the frequency and bandwidth of confined photons, all of which are essential to applications in active photonic integrated circuits.
Therefore, we have demonstrated the first high-speed all-optical switching of semiconductor microcavities made of GaAs-AlAs. We have “zapped” the cavities with an ultrashort fs laser pulse that shifted the cavity resonance to a higher frequency in a few ps, and the switched state relaxed with a time constant of 50 ps.
Recently, we have managed to switch cavity resonances by means of the near-instantaneous electronic Kerr effect. As a result, a whole on-off switching event is only limited by the speed of light, and completed within less than 1 picosecond. We have used these features to repeatedly switch a microcavity, see Figure 1. This observation corresponds to single-channel switch speeds in excess of 1 THz, more than 100x faster than the switch speed in a modern computer!
Earlier, we have observed that curious phenomenon the frequency of light trapped inside a switched cavity can be red-shifted much more than the shift of the cavity resonance; hence the frequency change is not-adiabatic with the cavity, see Figure 2. We are currently busy to understand the physics behind this phenomenon.